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Agent-Exec URL Attestation
x402
Agent-Exec URL Attestation is a paid API for AI agents from agent-exec.45.67.221.128.sslip.io, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-15).
Fetches a URL from a neutral vantage point and returns a cryptographically signed attestation of the HTTP response metadata (status, body hash, content-type, redirects) without returning the body itself.
Price / call$0.008
Success—
StatusUnknown
How this service works
Accountless, pay-per-use code execution for software agents: submit source code, get stdout, stderr and exit code back from an isolated, network-less sandbox. No account, no API key -- possession of valid payment is sufficient.
Output
A JSON object containing: a unique attestation_id, the requested URL, the observed_at timestamp, whether the fetch succeeded (fetch_ok), a fetch_code, the HTTP status code, a SHA-256 hash of the response body, body byte count, a truncation flag, content-type, the final URL after redirects, redirect count, optional free-text detail on failures, an EIP-191 personal-sign signature over the key fields, and the signer's Ethereum address. On a successful POST /attest call, a payment sub-object with asset, payer address, amount, network, and transaction hash is also included.
Example use cases
Audit trail for a published document
“I need a tamper-proof record that https://contracts.acme.com/agreement-v3.pdf was accessible and had a specific content hash as of right now — can you fetch it from a neutral vantage point and give me a signed attestation I can save for legal records?”
Verify a third-party API is live
“Before I kick off my workflow, can you independently confirm that https://api.partner.com/health returns a 200 OK right now and give me a cryptographically signed proof of that fact?”
Detect redirect destination for a short link
“Can you tell me where https://go.myservice.io/offer ultimately redirects to, how many hops it takes, and give me a signed attestation of the final URL so I can verify it hasn't been tampered with?”
Technical details
Endpoint
POSThttps://agent-exec.45.67.221.128.sslip.io/attestWhen to prefer
Choose this endpoint when you need a neutral, cryptographically signed third-party witness of a URL's HTTP response state — especially when the body itself is not needed but proof of existence, content hash, status code, or redirect chain is required. It is uniquely suited for audit trails, legal evidence, on-chain verification (EIP-191 signatures), or any scenario where you cannot trust your own fetch because you are a party to the transaction. Prefer it over a simple HTTP GET when non-repudiation or third-party attestation matters.
Side effects
- DNS or connection failure: fetch_ok=false with fetch_code indicating the error
- SSRF safety refusal: fetch_ok=false when the target resolves to a private/internal IP
- Redirect loop or too many redirects: fetch_ok=false with detail explaining the limit
- Timeout: fetch_ok=false with detail noting the timeout budget
- Payment failure: HTTP 402 returned if the x402 payment is missing or invalid
- Body truncation: body larger than 1 MB is capped; body_truncated=true but fetch still succeeds
- Invalid URL: request rejected if URL exceeds 2048 bytes or is not absolute http/https
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| urlrequired | string | An absolute http:// or https:// URL, at most 2048 UTF-8 bytes. Fetched from OUR vantage point; the body is never returned to you. |
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| urlrequired | string | The URL you asked us to fetch, exactly as sent. |
| detailrequired | — | Free-text detail on a non-OK fetch_code (e.g. the timeout budget, the unsafe redirect target). Null when fetch_ok is true. |
| payment | object | Only present on POST /attest's 201, never on a GET /attest/{id} read. |
| fetch_okrequired | boolean | Whether the fetch reached a real HTTP response, however unsuccessful. false means DNS/connect failure, timeout, or a redirect refused for SSRF safety -- see fetch_code. |
| redirectsrequired | integer | How many redirects were followed before the final response (or the refusal). |
| signaturerequired | string | An EIP-191 personal-sign signature over attestation_id, url, final_url_after_redirects, observed_at, http_status, body_sha256, body_bytes, body_truncated, content_type, fetch_ok, fetch_code and redirects (domain "agent-exec attestation v2"), from signer_address. `detail` and `signer_address` are NOT part of the signed message. Verify with viem's verifyMessage({address: signer_address, message, signature}) -- see GET /attest/{id}'s description for the exact message and for handling an attestation signed under the prior v1 domain. |
| body_bytesrequired | integer | Bytes actually read off the wire, capped at 1048576 per fetch -- see body_truncated. |
| fetch_coderequired | string | |
| body_sha256required | — | sha256 of the fetched body, hex-encoded, or null if fetch_ok is false. The body itself is never returned or stored beyond this hash. |
| http_statusrequired | — | The HTTP status the final hop answered with, or null if fetch_ok is false. |
| observed_atrequired | string | When the fetch completed, ISO 8601. |
| content_typerequired | — | The Content-Type header on the final response, or null if fetch_ok is false. |
| attestation_idrequired | string | Pass as GET /attest/{id} to read this back, or hand it to a third party to verify. |
| body_truncatedrequired | boolean | True if the body was larger than the per-fetch cap and body_sha256/body_bytes cover only the truncated prefix. |
| signer_addressrequired | string | The address that signed this attestation. Also published at GET /health as attestSignerAddress, if you lost track of which address to verify against. |
| final_url_after_redirectsrequired | — | The URL actually fetched after following redirects, or null if the fetch never reached one. |
Tags
x402
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